Raggy, I know some really brilliant songwriters, and I also have an idea of what happens in a real live tradition; the deviation from the authored words may appeal to some people more than the original; and that's their prerogative. The author can put it out, but the power is with the hearers. They are writing their own songs, starting with what they hear.

You'll possibly challenge my understanding of "real live tradition". My experience was the Irish music scene in Manchester in the 70s. Irish music was in transition, there was the established scene (Comhltas), Michael Coleman records on 78, Leo Rowsome and Seamus Ennis and all that available on record. There were the musicians from Ireland, labourers for the most part, a couple of young monks too, old fellers like Jimmy Taylor with his wrecked face and arthritic knobbly fingers who played like an angel, or Pack Dyer!!!. And us neophytes. And the tunes they knew, and the ones we got from the Chieftains, Ceoltori Laighinn (spelling?), Sean O'Riada, Geordies and morrismen who joined the session with their own tunes with spicy flavours... well, it was changing as we played. It's dynamic, not fossilised.

And if a variant of a perfect poem appeals better to the singer, and more importantly to the singer's audience (whoever they may be - you can't dictate that only authorised people should be listening), it will supersede the crafted original - for that audience. You can grumble all you like, but you won't convince them. And the original is still there, for those who prefer it.